This invention relates to magnets for generating a uniform magnetic force. More specifically, the invention relates to new magnets capable of imparting a uniform magnetic force in a predetermined space in a variety of instances such as synthesizing a substance, growing crystals, etc.
In a magnetic field generated by a magnet, a substance receives a magnetic force which varies in proportion to:
(Intensity of the magnetic field)xc3x97(gradient of intensity of the magnetic field:gradient of the magnetic field)
The magnetic force is utilized, for example, for separating empty cans by using magnet and in a process for magnetic separation such as removing impurities from industrial water.
The magnetic force is a physical quantity that acts not only on a ferromagnetic material such as iron but also on all substances that exhibit diamagnetism or paramagnetism. In recent years, powerful magnets have been produced by utilizing a superconductor to obtain a magnetic force which is far greater than those obtained thus far, and have been utilized as a variety of reaction control factors.
In practice, however, magnetic force that spontaneously exists around a magnet varies in space, and cannot be utilized for physical and engineering purposes. In order to utilize the magnetic force for the reaction processes, therefore, it becomes necessary to design the intensity and shape of a magnetic field by combining magnets to control the magnitude and distribution of the magnetic force in a sufficiently wide space.
A magnetic force that is symmetrical relative to an axis can be expressed, for example, by the following formula,       Fz    =          x      ⁡              (                              Hr            ⁢                                          ∂                Hr                                            ∂                z                                              +                      Hz            ⁢                                          ∂                Hz                                            ∂                z                                                    )                  Fr    =          x      ⁡              (                              Hr            ⁢                                          ∂                Hr                                            ∂                r                                              +                      Hz            ⁢                                          ∂                Hz                                            ∂                r                                                    )            
where "khgr" is a volume susceptibility, and H is an intensity of the magnetic field.
The term uniform magnetic force means a magnetic force Fz that is constant in the axial direction in a given space, and a magnetic force Fr, which is an error component in the radial direction, is as small as possible. In an isotropic substance, a magnetic flux density B varies in proportion to the intensity of the magnetic field. To generate a magnetic force that is spatially uniform, therefore, the magnet must satisfy the following formulas,             Fz      xe2x80x2        =                            Br          ⁢                                    ∂              Br                                      ∂              z                                      +                  Bz          ⁢                                    ∂              Bz                                      ∂              z                                          =      constant                  Fr      xe2x80x2        =                            Br          ⁢                                    ∂              Br                                      ∂              r                                      +                  Bz          ⁢                                    ∂              Bz                                      ∂              r                                          →      O      
There have heretofore been proposed and practically used a magnet that generates a uniform magnetic field like an NMR magnet and a magnet that generates a uniform magnetic field gradient like quadrupole magnets in an accelerator. However, no magnet has ever existed for controlling the (magnetic field)xc3x97(gradient of the magnetic field) as represented by the above formula for obtaining a field of uniform magnetic force. With the existing technology, therefore, the distribution of the magnetic force is not spatially uniform, and the magnetic force varies greatly depending upon the positions even in a working space for synthesizing a substance or for growing crystals. In a strict sense, the substance could not be synthesized or the crystals could not be grown while controlling the magnetic force.
It is therefore an assignment of this invention to provide novel magnets for generating a uniform magnetic force that make it possible to spatially uniformalize the magnetic force as the (magnetic field)xc3x97(gradient of the magnetic field) depending upon a change in the magnetic field by eliminating the above problems inherent in the prior art.
In order to solve the above assignment, the invention of this application provides magnets for generating a uniform magnetic force, comprising one or more main magnets formed by arranging a single magnet or plural magnets, and auxiliary magnets for uniformalizing the magnetic force of the main magnets in a predetermined space.
The invention of this application further provides the magnets for generating a uniform magnetic force, wherein the main magnets are air-core magnets, and the air core serves as the predetermined space, provides the magnets for generating a uniform magnetic force, wherein the auxiliary magnets are air-core magnets, provides the magnets for generating a uniform magnetic force, wherein the main magnets and the auxiliary magnets are electromagnets, and provides the magnets for generating a uniform magnetic force, wherein the positions of the auxiliary magnets can be varied relative to the main magnets.